Rubella virus nomenclature update: 2013.

Virological surveillance data on rubella viruses are used to track progress towards the goal of eliminating rubella, to help with case classification, and to document transmission pathways. This report updates the existing documentation and incorporates the increase in rubella data generated by the WHO Measles and Rubella Laboratory Network (LabNet) in the past 5 years. The nomenclature to describe the genetic diversity of wild-type rubella viruses was proposed initially in 2005 and was revised in 2007.